TCA9539_15 Datasheet, PDF (15/42 Pages) Texas Instruments – Low Voltage 16-Bit I2C and SMBus Low-Power I/O Expander

www.ti.com
8 Detailed Description
TCA9539
SCPS202B – OCTOBER 2009 – REVISED OCTOBER 2015
8.1 Overview
The TCA9539 is a 16-bit I/O expander for the two-line bidirectional bus (I²C) designed for 1.65-V to 5.5-V V_CC
operation. It provides general-purpose remote I/O expansion for most microcontroller families via the I²C
interface [serial clock (SCL), serial data (SDA)].
The TCA9539 consists of two 8-bit Configuration (input or output selection), Input Port, Output Port, and Polarity
Inversion (active-high or active-low operation) registers. At power-on, the I/Os are configured as inputs. The
system master can enable the I/Os as either inputs or outputs by writing to the I/O configuration register bits. The
data for each input or output is kept in the corresponding Input or output register. The polarity of the Input Port
register can be inverted with the Polarity Inversion register. All registers can be read by the system master.
The system master can reset the TCA9539 in the event of a time-out or other improper operation by asserting a
low in the RESET input. The power-on reset puts the registers in their default state and initializes the I²C/SMBus
state machine. Asserting RESET causes the same reset/initialization to occur without depowering the part.
The TCA9539 open-drain interrupt (INT) output is activated when any input state differs from its corresponding
Input Port register state and is used to indicate to the system master that an input state has changed.
INT can be connected to the interrupt input of a microcontroller. By sending an interrupt signal on this line, the
remote I/O can inform the microcontroller if there is incoming data on its ports without having to communicate via
the I²C bus. Thus, the TCA9539 can remain a simple slave device.
The device outputs (latched) have high-current drive capability for directly driving LEDs. The device has low
current consumption.
The TCA9539 is identical to the PCA9555, except for the removal of the internal I/O pullup resistor, which greatly
reduces power consumption when the I/Os are held low, replacement of A2 with RESET, and a different address
range. The TCA9539 is similar to the PCA9539 with lower voltage support (down to V_CC = 1.65 V), and also
improved power-on-reset circuitry for different application scenarios.
Two hardware pins (A0 and A1) are used to program and vary the fixed I²C address and allow up to four devices
to share the same I²C bus or SMBus.
Copyright © 2009–2015, Texas Instruments Incorporated
Product Folder Links: TCA9539
Submit Documentation Feedback
15